Carbonyl compounds, methods of making the same, and their use as fragrances and fragrance-enhancing additives

ABSTRACT

Carbonyl compounds derived from the reaction of alkyl cyclopentenols and vinyl ethers are described. The carbonyl compounds described have excellent fragrance properties, and their use as fragrances and/or fragrance-enhancing compounds is also described. Processes for the preparation of the carbonyl compounds are described as well.

BACKGROUND OF THE INVENTION

Judging by demand, many natural perfumes are available in totallyinadequate quantities. For example, 5,000 kg of rose blossoms arerequired to produce 1 kg of rose oil. The consequences are a seriouslylimited annual world production and a high price. Accordingly, it isclear that the perfume industry has a constant need for new perfumeswith interesting notes in order to add to the range of naturallyavailable perfumes, to make the necessary adaptations to changingfashion trends and to be able to cover the constantly increasing demandfor improvements in the odor of products of everyday use, such ascosmetics and cleaners.

In addition, there is generally a constant demand for synthetic perfumeswhich can be favorably produced in a consistent quality and which havedesirable olfactory properties, i.e. pleasant, close-to-natureand—qualitatively—novel odor profiles of sufficient intensity, and whichare capable of favorably influencing the smell of cosmetic products andconsumer goods. In other words, there is a constant need for compoundswhich have characteristic new odor profiles and, at the same time, highstaying power, intensity of odor and emanative power.

BRIEF SUMMARY OF THE INVENTION

The present invention relates, in general, to carbonyl compounds with aparticular structure, and to a process for their production and theiruse as perfumes.

It has been found that compounds corresponding to general formula (I)meet the requirements stated above in every respect and mayadvantageously be used as perfumes with differently nuanced odor notescharacterized by high staying power.

In a first embodiment, the present invention relates to carbonylcompounds corresponding to general formula (I):

in which R¹ is hydrogen or a C₁₋₅ alkyl group, R² and R³ independentlyof one another represent hydrogen or a C₁₋₃ alkyl group, a C═C doublebond is present in one of the positions C-1/C-2, C-2/C-3 or C-1/C-6 andR⁴ is either hydrogen or—if the C═C double bond is in the C-2/C-3position—is hydrogen or a C₁₋₃ alkyl group.

2-(2′-n-hexylcyclopent-2′-en-1′-yl)-acetaldehyde,2-(2′-n-hexylcyclopent-2′-en-1′-yl)-propionaldehyde and(2-n-hexylcyclopent-2-en-1 -yl)-acetone are most particularly preferred.

The compounds corresponding to formula (I) may be prepared by any of themethods known to the preparative organic chemist. According to theinvention, however, they are prepared in particular from special allylalcohols, the 2-alkylcyclopent-2-en-1-ols, which may optionally containanother alkyl group in the 3-position and which, when reacted withspecial vinyl ethers, give intermediate products that are accessible to[3,3]-sigmatropic rearrangements. In the case of the rearrangementproducts, the C═C double bond formed primarily in the five-membered ringmay be subsequently shifted towards the carbonyl group.

2-Alkylcyclopent-2-en-1-ones—products generally obtainable commerciallyunder such names as isojasmone, sedamon, cis-jasmone, dijasmone,dihydrojasmone or dihydroisojasmone or by aldol condensation ofcyclopentanone with various aldehydes—can be selectively reduced to thecorresponding allyl alcohols, the 2-alkylcyclopent-2-en-1-ols, withcomplex hydrides such as, for example, alkali metal borohydrides oraluminium hydrides, or by Meerwein-Ponndorf reduction with aluminiumalcoholates.

The present invention also relates to a process for the production ofcarbonyl compounds (I) in which alkyl cyclopentenols corresponding togeneral formula (II):

in which R¹ and R⁴ are as defined above, are reacted with vinyl etherscorresponding to general formula (III):

in which R² and R³ are as defined above. The “Alkyl” moiety in formula(III) is methyl, ethyl, propyl, C₄₋₁₀ alkyl and cycloalkyl.

Examples of suitable vinyl ethers are ethyl vinyl ether,2-methoxypropene, 1-propenyl ethyl ether, 2-propenyl ethyl ether,cyclohexyl vinyl ether.

DETAILED DESCRIPTION OF THE INVENTION

The compounds (I) are distinguished by a pronounced aldehydic characterto their odor with intensive green and fruit notes.

In perfume compositions, the compounds (I) strengthen harmony, emanationand also staying power, the quantities used being adapted to theparticular perfume note required taking the other ingredients of thecomposition into account.

The fact that the carbonyl compounds (I) have aldehydic green-fruitynotes was not foreseeable and, hence, is further confirmation of thegeneral experience that the olfactory properties of known perfumes donot allow any definitive conclusions to be drawn as to the properties ofstructurally related compounds because neither the mechanism of odorperception nor the influence of chemical structure on odor perceptionhas been sufficiently researched, so that it is not normally possible topredict whether modifications to the structure of known perfumes will infact lead to changes in their olfactory properties or whether thesechanges will be positive or negative.

Accordingly, the present invention also relates to the use of thecompounds (I) as perfumes.

By virtue of their odor profile, the compounds corresponding to formula(I) are also particularly suitable for modifying and enhancing knowncompositions. Particular emphasis is placed on their extreme intensityof odor which contributes quite generally towards refining thecomposition.

The compounds corresponding to formula (I) may be combined with manyknown perfume ingredients, for example other perfumes of natural,synthetic or partly synthetic origin, essential oils and plant extracts.The range of natural fragrances can thus include both high-volatilityand also medium-volatility and low-volatility components while the rangeof synthetic perfumes may include representatives of virtually everyclass of compounds. Examples are:

(a) natural products, such as tree moss absolue, basil oil, citrus oils,such as bergamot oil, mandarin oil, etc., mastix absolue, myrtle oil,palmarosa oil, patchouli oil, petitgrain oil, wormwood oil, myrrh oil,olibanum oil

(b) alcohols, such as farnesol, geraniol, linalool, nerol, phenylethylalcohol, rhodinol, cinnamic alcohol, sandalore[3-methyl-5-(2,2,3-trimethylcyclopent-3-en-1-yl)-pentan-2-ol], sandela[3-isocamphyl-(5)-cyclohexanol]

(c) aldehydes, such as citral, Helional®, α-hexyl cinnamaldehyde,hydroxycitronellal, Lilial®[p-tert.butyl-α-methyldihydrocinnamalde-hyde], methylnonyl acetaldehyde

(d) ketones, such as allylionone, α-ionone, β-ionone, isoraldein, methylionone

(e) esters, such as allylphenoxyacetate, benzyl salicylate, cinnamylpropionate, citronellyl acetate, citronellyl ethoxylate, decyl acetate,dimethylbenzyl carbinyl acetate, ethyl acetoacetate, hexenylisobuty-rate, linalyl acetate, methyl dihydrojasmonate, vetiverylacetate, cyclohexyl salicylate

(f) lactones, such as gamma-undecalactone, 1-oxaspiro[4.4]-nonan-2-oneand various other components often used in perfumery, such as musk,indole, p-methan-8-thiol-3-one, methyl eugenol, Ambroxan.

It is also remarkable how the compounds corresponding to formula (I)round off and harmonize the odor notes of a broad range of knowncompositions without unpleasantly dominating them in any way.2-(2′-n-hexylcyclopent-2′-en-1′-yl)-antaldehyde is particularlyemphasized in this regard.

The compounds according to the invention contain chirality centers sothat they may exist in various spatial forms. The compounds according tothe invention accumulate as mixtures of the corresponding isomers in thecourse of typical syntheses and are used in this form asperfumes/fragrances.

The compounds according to the invention or mixtures thereof may be usedin perfume compositions in quantities of 1 to 70% by weight, based onthe mixture as a whole. Mixtures of compounds (I) according to theinvention and compositions of this type may be used both for perfumingcosmetic preparations, such as lotions, creams, shampoos, soaps,emollients, powders, aerosols, toothpastes, mouthwashes, deodorants, andalso in alcohol-based perfumery (for example colognes, toilet waters,extracts). The compounds according to the invention or mixtures thereofmay also be used for perfuming commercial products, such as detergents,fabric softeners and textile treatment preparations. For perfuming thesevarious products, the compositions are added in an olfactorily effectivequantity, more particularly in a concentration of 0.05 to 2% by weight,based on the product as a whole. However, these values are not intendedto represent limits because the experienced perfumer can also obtaineffects with even lower concentrations or can build up new complexeswith even higher doses.

EXAMPLE

A) Precursors

Example 1 Preparation of “Isojasmone” (2-n-hexyl-2-cyclopenten-1-one and2-n-hexylidenecyclopentan-1-one) Materials

210 g (2.5 moles) cyclopentanone

280 g (2.8 moles) n-hexanal

280 ml (0.25 mole) KOH solution, 5%

280 ml cyclohexane

300 g (0.3 mole) sulfuric acid, 5%

0.17 g p-toluenesulfonic acid

Method

The reaction was carried out in a 2-liter face-ground flask withbuilt-in internals and a turbine impeller (1000 r.p.m.). The 5% KOH andthe cyclohexane were introduced into the reactor first—under nitrogen at15° C. A solution of cyclopentanone and hexanal was added dropwise withstirring over a period of 2 hours at 15 to 20° C. After stirring for 2hours, the reaction mixture was neutralized with the sulfuric acid. Thereaction mixture was then transferred to a separation funnel and thephases were separated. The aqueous phase was discarded and thecyclohexane phase was washed with dist. water until neutral. Withoutdrying, the p-toluenesulfonic acid was added to the organic phase whichwas then heated under reflux on a water separator for the azeotropicdistillation of ca. 50 ml water. Another 0.8 g of p-toluenesulfonic acidwas added and another 7 ml water were removed from the circuit. Workingup:

The cyclohexane was distilled off and the 400 g of black residue weredistilled through an oil-heated thin-layer evaporator (jackettemperature 115-120° C./0.1 mbar).

In the subsequent fractional distillation in a spinning-band column, theproduct was isolated as an isomer mixture (compounds with an exo- andendocyclic double bond) in a yield of 45% of the theoretical.

Example 2 Isomerization of the 2-n-hexylidene Cyclopentanone to2-n-hexylcyclopent-2-en-1-one (According to J. G. Tillet, Chem. Rev. 76,747 (1976)]

Materials

332 g (2 moles) isojasmone (isomer mixture of Example 1)

2 l 1-butanol

0.2 l conc. hydrochloric acid

Method

The isojasmone and n-butanol were introduced into a 4-liter three-neckedflask equipped with a KPG stirrer, a dropping funnel, a jacketed coilcondenser and a temperature probe and the hydrochloric acid was addeddropwise at room temperature. A slight increase in temperature wasobserved. The reaction mixture was stirred for 3 hours at ca. 100° C.and then diluted with diethyl ether.

Working Up

The organic phase was separated off and washed with water, bicarbonatesolution and water and then dried over magnesium sulfate, filtered andconcentrated. 329.5 g of residue were weighed out. The material wasdistilled in a high vacuum in a 10 cm Vigreux column, giving 171.9 g of2-n-hexylcyclopent-2-en-1-one with a purity of more than 99%. The yieldamounted to 51.8% of the theoretical.

Example 3 Reduction of Isojasmone to Isojasmol (According to J. L.Luche, L. Rodriguez-Hahn, P. Grabbe, J.S.C. Chem. Comm., 1978, pp.601-2)

Materials

I) 167.8 g (1 mole) isojasmone (prepared in accordance with Example 2 orcommercial product, from example from Quest)

II) 373 g (1 mole) cerium(III) chloride heptahydrate

III) 38 g sodium borohydride

IV) 1.5 l methanol

Components I, II and IV were mixed at room temperature in a 4-literfour-necked flask. Component III was added in portions with vigorousstirring over a period of 3 hours, followed by stirring for 2 hours atroom temperature.

Working Up

Ca. 1 liter water was added to the mixture which was then extracted 4times with cyclohexane. The organic phase was dried over sodium sulfateand concentrated in a rotary evaporator.

The residue of 161.3 g of reaction mixture was distilled in a 15 cmVigreux column. 136.1 g of product with a gas chromatographicallydetermined purity of ca. 90% (73% of the theoretical) were obtained andwere used without further purification for subsequent syntheses.

Example 4 Preparation of 3-methyl-2-n-heptylcyclopent-2-en-1-one fromthe Henkel Perfume “Aldehyd 11/11”

Materials

170 g (1 mole) Aldehyd 11/11 (mixture of methyloctyl

acetaldehyde and undecanal)

125 g (1.2 mole) malonic acid

4 g ammonium acetate

400 ml toluene

Method

All the components were rapidly combined in a 1-liter three-necked flaskequipped with a stirrer, internal thermometer and Dean-Starck waterseparator and heated with vigorous stirring to reflux temperature. After3 hours, 18 ml water had been azeotropically distilled off and separatedoff. Ca. 280 g toluene were then distilled off at an oil bathtemperature of 50° C. and the residue was distilled in a short-pathstill (jacket temperature 205° C., 0.03 mbar). 115 g (54.3% of thetheoretical) of 4-methyldodec-3-enoic acid were obtained.

115 g of 85% sulfuric acid were added with stirring to the 115 g of4-methyldodec-3-enoic acid in a 500 ml three-necked flask and themixture was heated for 4 hours to 90° C. For working up, the reactionmixture was carefully stirred into 500 ml water, extracted three timeswith 250 ml ether and the combined ether phases were washed withbicarbonate solution until neutral, dried over sodium sulfate andconcentrated in a rotary evaporator. The residue of 92 g was distilledin a bulb-tube still at 180° C./0.03 mbar pressure, 66 g (57.4% of thetheoretical) of 5-methyl-5-n-octylbutyrolactone and 5 g residue beingobtained.

In a 1-liter three-necked flask, 200 g of polyphosphoric acid (Fluka)were heated with stirring under nitrogen to 100° C. and 63.6 g (0.3mole) of 5-methyl-5-n-octyl butyrolactone were added dropwise over aperiod of 45 minutes. The mixture was stirred for 1.5 hours at 100° C.and then cooled. The product was extracted with 3×150 ml diethyl ether,washed with bicarbonate solution until neutral, dried over sodiumsulfate and concentrated in a rotary evaporator. 60 g residue (GC purity78%) were predistilled in a bulb-tube still (furnace temperature 150°C., 0.03 mbar). The 58 g obtained were distilled in a 15 cm long Vigreuxcolumn and the main runnings of 32.5 g (purity 95%) were fractionated ina spinning-band column. 20.8 g of 100% pure3-methyl-2-n-heptyl-2-cyclopenten-1-one (Bp. 74-76° C./0.08 mbar) wereobtained. Odor description: jasmone, diffusive, flowery, celery note.

B) Compounds According to the Invention

Example 5 Reaction of Isojasmol to2-(2′-n-hexylcyclopent-2′-en-1′-yl)-acetaldehyde

Materials

433.1 g (2 moles) isojasmol (prepared in accordance with Example 3)

173.1 g (2.4 moles) ethyl vinyl ether (99%, Fluka)

18 g (0.24 mole) propionic acid

Method

The components were introduced under nitrogen into a 2-liter V2A steelautoclave insert and stirred in an autoclave for 4 hours at 180° C./50bar nitrogen. Another 18 g of propionic acid were then added to thereaction mixture, followed by stirring for another 4 hours at 200° C./60bar nitrogen. As was readily established by GC, a number of intermediateproducts were formed at 180° C. and were converted at 200° C. partlyinto the educt isojasmol and partly into the required product (2 maincomponents).

Working up

After low-boiling components had been distilled off, 459.2 g of crudeproduct were used for distillation in a high vacuum in a spinning-bandcolumn. 79 g of main runnings distilled over at head temperatures of64-73° C./.04 mbar (2 isomers, GC purity 60%). This low purity wasolfactorily acceptable. Odor description: aldehydic, green, ozone,flowery, fruity, water melon, fatty.

Example 6 Reaction of Isojasmol to2-(2′-n-hexylcyclopent-2′-en-1′-yl)-propionaldehyde

Materials

84.0 g (0.5 mole) isojasmol (prepared in accordance with Example 3)

56.0 g (0.65 mole) ethyl-1-propenyl ether (Fluka)

1.5 g propionic acid (Merck)

Method

As in Example 5, the components were first introduced into a V2aA steelautoclave insert, heated to 210° C. under an initial nitrogen pressureof 10 bar and stirred for 8 hours. The pressure rose to 30 bar.

Working Up

The crude product was freed from excess ether in a rotary evaporator and95.4 g of a dark brown liquid were distilled in a high vacuum through a30 cm packed column (Brunswick coils). The main runnings of 24.5 g of alight yellow liquid (Bp. 62-93° C./0.08 mbar) were fractionated in aspinning-band column. 15.4 g of2-(2-n-hexylcyclopent-2-en-1-yl)-propionaldehyde (Bp. 60-64° C./0.04mbar) were obtained. The gas chromatographic purity was 93%. Odordescription: green, aldehydic, flowery, emanative (diffusive), fruity,melon, ozone.

Example 7 Reaction of isojasmol to(2-n-hexylcyclopent-2-en-1-yl)-acetone

Materials

84.0 g (0.5 mole) isojasmol (prepared in accordance with Example 3)

56.0 g (0.78 mole) 2-methoxypropene (Janssen)

1,5-propionic acid (Merck)

Method

The components were introduced into a V2A steel autoclave insert under10 bar nitrogen and heated with stirring for 8 hours to 210° C. (30 barworking pressure).

Working Up

The crude product was freed from excess ether and the residue, 85.8 g ofa dark brown liquid, was used for distillation in a high vacuum in a 30cm long column packed with Brunswick coils. 37.3 g of a light yellowliquid (Bp. 80-94° C./0.08 mbar) were obtained as main runnings and werefractionated in a spinning-band column. 33.4 g of a light green liquid,Bp. 85-87° C./0.06 mbar, were obtained. Odor description: flowery,diffusive, spicy, celery note, mushroomy.

Example 8 Preparation of (2′-n-hexylcyclopentylidene)-acetaldehyde from2-n-heylcyclopentan-1 -one

Step 1

Materials

83.9 g (0.5 mole) jasmatone (2-n-hexylcyclopentan-1-one; Quest)

111.0 g (0.75 mole) triethyl orthoformate

101.8 mg potassium hydrogen sulfate

500 ml ethanol, water-free

Apparatus

1-liter stirred reactor, KPG stirrer, thermometer, reflux condenser

Method

The apparatus was dried and heated with a hot air blower while aconstant stream of nitrogen was passed through (25 ml/min.). Thejasmatone was introduced first in 200 ml. abs. ethanol, after which thetriethyl orthoformate, the potassium hydrogen sulfate and the remaining300 ml of ethanol were added. The withdrawal of educt and the formationof several products was monitored by GC. After 5 hours, the reaction wasterminated and the reaction mixture was neutralized by addition of asmall quantity of sodium methanolate solution. The mixture was combinedwith another two reaction mixtures prepared under the same conditionsand the total of 411.5 g of crude product was distilled in a 20 cm longVigreux column. 252.3 g of jasmatone diethyl ketal(1,1-diethoxy-2-n-hexyl cyclopentane) (GC purity 97% (2 peaks), Bp.95-98° C./0.08 mbar) were obtained as main runnings.

Step 2

Materials

31.22 g (1.34 mole) 1,1-diethoxy-2-n-hexyl cyclopentane (prepared inaccordance with step 1)

144.9 g (2 moles) ethyl vinyl ether

115 ml zinc (II) chloride solution, 10% in ethyl acetate

Apparatus

1-liter stirred reactor, reflux condenser, dropping funnel, thermometer

Method

The 1,1-diethoxy-2-n-hexyl cyclopentanone and the zinc chloride solutionwere introduced first with stirring and heated to 40-45° C. The ethylvinyl ether was continuously added to this mixture over a period of 2hours. After the addition, the mixture was stirred for 3 hours at 40-50°C.

Working Up

The reaction mixture was washed twice with 0.1 molar sodium hydroxidesolution and twice with water, dried over sodium sulfate andconcentrated in a rotary evaporator. Distillation in a 20 cm longVigreux column produced 61.5 g of ca. 62%1-(2,2-diethoxyethyl)-1-ethoxy-2-hexyl cyclopentane (2 diastereomers,Bp. 130-140° C./0.04 mbar).

Step 3

Materials

61.5 g (0.121 mole) 1-(2,2-diethoxyethyl)-1-ethoxy-2-hexyl cyclopentane(prepared in accordance with step 2)

18.7 g (0.41 mole) formic acid

5.0 g (0.074 mole) sodium formate

8.0 g (0.443 mole) water, demineralized

Apparatus

250 ml stirred reactor, PT 100 (stainless steel temperature sensor),reflux condenser, dropping funnel

Method

The formic acid/sodium formate buffer was introduced first and heated toreflux temperature (113° C.). The 61.5 g of1-(2,2-diethoxyethyl)-1-ethoxy-2-hexylcyclopentane were continuouslyadded with stirring over a period of 1.15 hours at reflux temperature.The mixture was kept at reflux temperature (now 78° C.) for another 2hours. Working up:

The mixture was stirred into 200 ml of ice water and the organic phasewas separated off. The aqueous phase was then extracted with 3×100 mldiethylether and the combined organic phases were washed until neutral,dried over magnesium sulfate and concentrated in a rotary evaporator.The fractionation of 55 g of crude product in a spinning-band columnproduced product fractions with different GC purities (total quantity ofthe fractions: 38.5 g).

Fraction 3 with a composition of 49/15/19 GC% (Bp. 63-82° C./0.08 mbar;2-n-hexylcyclopentylidene acetaldehyde and isomers with a double bond inthe 1- or 2-position) were olfactorily evaluated as comparable with theodor of the compound of Example 6: green, aldehydic, fresh, less melonand ozone than in Example 6. A fatty note was additionally detected inthe other fractions.

What is claimed is:
 1. A compound corresponding to general formula (I):

wherein R¹ represents a hydrogen atom or a C₁₋₅ alkyl group, whereineach of R² and R³ independently represents a hydrogen atom or a C₁₋₃alkyl group, wherein a carbon-carbon double bond is present in aposition selected from the group consisting of C¹/C², C²/C³ and C¹/C⁶;and wherein R⁴ represents a hydrogen atom or a C₁₋₃ alkyl group when thecarbon-carbon double bond is present in the C²/C³ position.
 2. Thecompound according to claim 1, wherein R¹ represents a C₄ alkyl group,the carbon-carbon double bond is present in the C²/C³ position, and eachof R², R³ and R⁴ represents a hydrogen atom.
 3. The compound accordingto claim 1, wherein R¹ represents a C₄ alkyl group, the carbon-carbondouble bond is present in the C²/C³ position, R³ represents a methylgroup, and each of R² and R⁴ represents a hydrogen atom.
 4. The compoundaccording to claim 1, wherein R¹ represents a C₄ alkyl group, thecarbon-carbon double bond is present in the C²/C³ position, R²represents a methyl group, and each of R³ and R⁴ represents a hydrogenatom.
 5. A process for preparing compounds corresponding to generalformula (I):

wherein R¹ represents a hydrogen atom or a C₁₋₅ alkyl group, whereineach of R² and R³ independently represents a hydrogen atom or a C₁₋₃alkyl group, wherein a carbon-carbon double bond is present in aposition selected from the group consisting of C¹/C², C²/C³ and C¹/C⁶;and wherein R⁴ represents a hydrogen atom or a C₁₋₃ alkyl group when thecarbon-carbon double bond is present in the C²/C³ position; said processcomprising:

(a) providing an alkyl cyclopentenol according to general formula (II): wherein R¹ and R⁴ are as defined above; (b) providing a vinyl etheraccording to general formula (III):

 wherein R² and R³ are as defined above, and wherein the Alkyl grouprepresents a linear or branched C₁₋₁₀ alkyl or cycloalkyl group; and (c)reacting the alkyl cyclopentenol and the vinyl ether.
 6. The processaccording to claim 5, wherein R¹ represents a C₁₋₅ alkyl group.
 7. Theprocess according to claim 5, wherein R¹ represents a C₄ alkyl group,and each of R², R³ and R⁴ represents a hydrogen atom.
 8. The processaccording to claim 5, wherein R¹ represents a C₄ alkyl group, R³represents a methyl group, and each of R² and R⁴ represents a hydrogenatom.
 9. The process according to claim 5, wherein R¹ represents a C₄alkyl group, R² represents a methyl group, and each of R³ and R⁴represents a hydrogen atom.
 10. A method of enhancing the fragranceproperties of a composition, said method comprising: (a) providing acomposition with fragrance properties to be enhanced; (b) providing thecompound according to claim 1; and (c) combining a fragrance-enhancingeffective amount of the compound and the composition.
 11. A method ofproviding a fragrance to a composition, said method comprising: (a)providing a composition to be enhanced with a fragrance; (b) providingthe compound according to claim 1, and (c) combining afragrance-providing effective amount of the compound and thecomposition.
 12. A perfume composition comprising a compound accordingto general formula (I):

wherein R¹ represents a hydrogen atom or a C₁₋₅ alkyl group, whereineach of R² and R³ independently represents a hydrogen atom or a C₁₋₃alkyl group, wherein a carbon-carbon double bond is present in aposition selected from the group consisting of C¹/C², C²/C³ and C¹/C⁶;wherein R⁴ represents a hydrogen atom or a C₁₋₃ alkyl group when thecarbon-carbon double bond is present in the C²/C³ position, and whereinthe compound is present in an amount of from 1 to 70% by weight, basedon the weight of the perfume composition.
 13. The perfume compositionaccording to claim 12, wherein R¹ represents a C₄ alkyl group, thecarbon-carbon double bond is present in the C²/C³ position, and each ofR², R³ and R⁴ represents a hydrogen atom.
 14. The perfume compositionaccording to claim 12, wherein R¹ represents a C₄ alkyl group, thecarbon-carbon double bond is present in the C²/C³ position, R³represents a methyl group, and each of R² and R⁴ represents a hydrogenatom.
 15. The perfume composition according to claim 12, wherein R¹represents a C₄ alkyl group, the carbon-carbon double bond is present inthe C²/C³ position, R² represents a methyl group, and each of R³ and R⁴represents a hydrogen atom.